Locomotive electrical output

[dekemd]

Thanks guys. So we're talking in the 2.5 to 3 Megawatt range. That's what I wanted to know. But you did bring up another question. Tell me about the series to parallel transition. I understand series and parallel circuits. What I want to know is what advantages you gain by running the motors is series and then parallel.

Derrick

[Anonymous]

An SD40-2 does transition much smoother, you will still see the fluctuation in the amp meter when the transition occurs. It is not done electronically there are still serial and parallel contactors in the lower electrical cabinet.

[Anonymous]

An SD40-2 does transition much smoother, you will still see the fluctuation in the amp meter when the transition occurs. It is not done electronically there are still serial and parallel contactors in the lower electrical cabinet.

[zardoz]

I wi***o continue with this only for my own information; I am not questioning anything either pfrench or oltmannd have said.

I remeber back when operating old EMD equipment (gp7, gp30; gp35 etc) that when accelerating a train, the engineer had to be aware of the speed at which each locomotive made 'transition' from series to parallel. If more than one locomotive made transition at the same time, a break-in-two was a real possibility due to two (or more) locomotives temporarily losing power (during the actual change from series to parallel) and then both coming back on line. During the power drop, it was a possibility that (depending on grade and other factors) that a small portion of the train could run-in a bit, then when power came back, the locomotives and the few cars that ran in would accelerate quickly. When the slack would finally get to the point of being fully stretched agian, the train would break at that point.

When we got the (then) new SD40-2, the transition speed was no longer an issue due to the fact there was no 'transition point' Perhaps the transition was done electronically and modified so as to not cause the above-mentioned problem. But I never noticed and change in locomotive operating conditions as the train accelerated.

I would appreciate any info from other engineers regarding this. In the meanwhile, I'm going to dig thru my old RR stuff and see if I can find my operating manual for the SD's.

[zardoz]

I wi***o continue with this only for my own information; I am not questioning anything either pfrench or oltmannd have said.

I remeber back when operating old EMD equipment (gp7, gp30; gp35 etc) that when accelerating a train, the engineer had to be aware of the speed at which each locomotive made 'transition' from series to parallel. If more than one locomotive made transition at the same time, a break-in-two was a real possibility due to two (or more) locomotives temporarily losing power (during the actual change from series to parallel) and then both coming back on line. During the power drop, it was a possibility that (depending on grade and other factors) that a small portion of the train could run-in a bit, then when power came back, the locomotives and the few cars that ran in would accelerate quickly. When the slack would finally get to the point of being fully stretched agian, the train would break at that point.

When we got the (then) new SD40-2, the transition speed was no longer an issue due to the fact there was no 'transition point' Perhaps the transition was done electronically and modified so as to not cause the above-mentioned problem. But I never noticed and change in locomotive operating conditions as the train accelerated.

I would appreciate any info from other engineers regarding this. In the meanwhile, I'm going to dig thru my old RR stuff and see if I can find my operating manual for the SD's.

[oltmannd]

You are all making this too complicated. The straight conversion from HP to KW is there is .746 KW per HP. Both are units of power.

However, a locomotive's HP is rated at the shaft going INTO the main generator/altenator. e.g. an SD60 is rated at 3838 HP under AAR std conditions, but only 3604HP (2689KW) comes out of the main generator as electrical energy headed for the traction motors.

In notch 8 - 904 RPM, a 10 pole AR10 alternator (EMD 40 series) makes 75Hz AC power. To use as an emergency generator, you'd have to operate it at 720 RPM, roughly notch 6, so output would be 60 Hz.

[oltmannd]

You are all making this too complicated. The straight conversion from HP to KW is there is .746 KW per HP. Both are units of power.

However, a locomotive's HP is rated at the shaft going INTO the main generator/altenator. e.g. an SD60 is rated at 3838 HP under AAR std conditions, but only 3604HP (2689KW) comes out of the main generator as electrical energy headed for the traction motors.

In notch 8 - 904 RPM, a 10 pole AR10 alternator (EMD 40 series) makes 75Hz AC power. To use as an emergency generator, you'd have to operate it at 720 RPM, roughly notch 6, so output would be 60 Hz.

[Anonymous]

I have never seen a locomotive that was permanently in parallel by design. I do remember having one that would not go back into series by because of a fault, at slow speeds it would not pull itself. I have seen some SD39s that were designed for the yard that did not have parallel contactors. I also remember having an SD40-2 that blew it's series contactor when it dropped down under heavy load.

If what you say were true when the amp meter read 4000 amps the traction motor you say is rated for 1500 amps would surely fry.

[Anonymous]

I have never seen a locomotive that was permanently in parallel by design. I do remember having one that would not go back into series by because of a fault, at slow speeds it would not pull itself. I have seen some SD39s that were designed for the yard that did not have parallel contactors. I also remember having an SD40-2 that blew it's series contactor when it dropped down under heavy load.

If what you say were true when the amp meter read 4000 amps the traction motor you say is rated for 1500 amps would surely fry.

[zardoz]

pfrench-
you may be right regarding the voltage change in relation to traction motor speed (counter-electro-motive-force). However, the ratings at full power starting a train moving or pulling uphill at maximum throttle at 3mph I believe are correct.

The traction motors on an SD40-2 are permanently in parallel, and the ammeter shows the electrical output only to traction motor #2, not the entire set.

[zardoz]

pfrench-
you may be right regarding the voltage change in relation to traction motor speed (counter-electro-motive-force). However, the ratings at full power starting a train moving or pulling uphill at maximum throttle at 3mph I believe are correct.

The traction motors on an SD40-2 are permanently in parallel, and the ammeter shows the electrical output only to traction motor #2, not the entire set.

[Anonymous]

I think your figures are a little high. First of all if you are putting 1500 amps per traction motor in series you would need (6X1500) 9000 amps. I have never seen an amp meter go to 9000 amps. The voltage is determined by the speed the motor is turning. The voltage at low speeds and high amps might be as low as 75 volts. At sixty mph the amps drop and the voltage then rises to your quoted 400 volts. On a newer SD or Dash 9 you can go into diagnostics and check the voltage and current at various speeds.

[Anonymous]

I think your figures are a little high. First of all if you are putting 1500 amps per traction motor in series you would need (6X1500) 9000 amps. I have never seen an amp meter go to 9000 amps. The voltage is determined by the speed the motor is turning. The voltage at low speeds and high amps might be as low as 75 volts. At sixty mph the amps drop and the voltage then rises to your quoted 400 volts. On a newer SD or Dash 9 you can go into diagnostics and check the voltage and current at various speeds.

[zardoz]

If memory serves...

The SD40-2 works on a 400 volt system. Each traction motor is rated for up to 1500 amps (short-time rating), and there are 6 traction motors on an SD.

As watts=volts x amps, you get 400x1500x6 = 3,600,000 or 3600kw.

FYI - at full power an sd40-2 uses up to 800 gallons of fuel per hour.

I do not know any specs for other locomotives.

[zardoz]

If memory serves...

The SD40-2 works on a 400 volt system. Each traction motor is rated for up to 1500 amps (short-time rating), and there are 6 traction motors on an SD.

As watts=volts x amps, you get 400x1500x6 = 3,600,000 or 3600kw.

FYI - at full power an sd40-2 uses up to 800 gallons of fuel per hour.

I do not know any specs for other locomotives.

[dekemd]

Our comm center has a backup generator in case of power outages. It's basically the same as a locomotive, diesel engine driving a generator. It's rated at around 150 kilowatts. What is an average locomotive capable of putting out as far as electrical power? Say a sd40-2 or a AC4400?

[dekemd]

Our comm center has a backup generator in case of power outages. It's basically the same as a locomotive, diesel engine driving a generator. It's rated at around 150 kilowatts. What is an average locomotive capable of putting out as far as electrical power? Say a sd40-2 or a AC4400?